Enhance make.jl to automatically produce a list of all relevant repositories

[fingolfin]

Work in progress. Some TODOs

• perhaps adjust description of some repositories
• set or adjust the "homepage URLs" set for several repositories
• find a way to list codecov links only for repositories that really use it (possibly via hard-coded allow or block list
• should the list be sorted differently (instead of alphabetically perhaps some repos should be forced to the top, e.g. Documenter)
• perhaps exclude some more repositories (or alternatively some should be archived)
  • DocumentationGeneratorRegistry (in light of Documentation Re-hosting Issues and Process for 2024 JuliaComputing/JuliaHub-Feedback#161 (comment))
• ...

[mortenpi]

Should maybe also remove this? Looks a but weird now, since it's followed by the heading directly:

Suggested change

JuliaDocs is the home for the following packages and repositories:

[mortenpi]

Generally, looks great though! Thank you @fingolfin!